Critical appraisal:Elsafi SH, Alqahtani NI, Zakary NY, Al Zahrani EM 2015 3

From Cancer Guidelines Wiki

Risk of bias assessment: diagnostic accuracy study

Patient Selection
Prior tests and any referral filters
Condition that defined entry into study
Setting
Patients who reported to two tertiary hospitals in the eastern region of Saudi Arabia – King Fahd Military Medical Complex (Dhahran, Saudi Arabia); and King Faisal Specialist Hospital (Dammam, Saudi Arabia) from June 2012 through May 2013.
Was a diagnostic case-control design avoided?
Yes
Consecutive or random sample?
Yes
Did the study avoid inappropriate exclusions?
Yes
Reasons
Patients who reported symptoms of disease of the lower gastrointestinal tract were excluded.
If comparing more than one index test was the design fully paired or paired randomly?
Not applicable
If a paired randomised design was used, was allocation to groups concealed and was the generation of allocation sequence adequate?
Not applicable
What is the risk that the selection of participants introduced bias?
Low
Comments
Index test 1
Describe index test and how it was conducted and interpreted
ColoScreen® was performed according to the manufacturer’s instructions. In brief, using the applicator, very thin smears of stool from different sites were applied in boxes A and B, and they were allowed to air dry before the cover was closed. The perforated window on the back of the slide was then opened and two drops of ColoScreen developer was applied to the back of boxes A and B before reading the results after 30 seconds and within 2 minutes. Any trace of blue color, within or on the outer rim of the specimen, was reported as positive for occult blood.
Were the index test results interpreted without knowledge of the results of the reference standard?
Unclear
If a threshold was used, was it pre-specified?
Yes
If two tests are being compared, have they been assessed independently / blind to each other?
Unclear
What is the risk that the conduct or interpretation of the index test introduced bias?
Unclear
Comments
Blinding not described
Index test 2
Describe index test and how it was conducted and interpreted, if applicable
RAPEPKT313 was performed according to the manufacturer’s instructions. In brief, a stool specimen is collected into the sampling tube containing extraction solution. After mixing the stool sample, a test strip is screwed into the sampling tube by breaking the bottom seal of the sampling tube while maintaining a vertical position, and it was allowed to settle for approximately 1 minute. The extracted fecal solution flows into the bottom space of the test strip and triggers the start of the FOB immunoassay. If human hemoglobin is present at a level higher than 50 ng/mL in a fecal sample extract, a red colored band appears in the test region, which is located in the lower half of the test membrane. A similar colored band must appear in the control region located in the upper-half of the test membrane, indicating that the test strip is functioning properly and the result is valid.
Were the index test results interpreted without knowledge of the results of the reference standard?
Unclear
If a threshold was used, was it pre-specified?
Yes
What is the risk that the conduct or interpretation of the index test introduced bias?
Unclear
Comments
Blinding not described
Reference Standard
Describe the reference standard and how it was conducted and interpreted
All participants underwent complete colonoscopy in one of the two hospitals. Colonoscopies were performed in a standard fashion by experienced gastroenterologists. The location and size of all polypoid lesions were recorded and the tumor specimens were pathologically classified as previously described.
Is the reference standard likely to correctly classify the target condition?
Yes
Were the reference standard results interpreted without knowedge of the results of the index test/s?
Unclear
Was the reference test standard independent of the index test?
(i.e. the index test did not form part of the reference standard)
Yes
What is the risk that the reference standard, its conduct or interpretation introduced bias?
Unclear
Comments
Blinding not described
Flow and timing
Describe any patients who did not receive the index test(s) and/or reference standard or who were excluded from the 2x2 table
All patients received all tests
Describe the time interval and any interventions between index test(s) and reference standard
Timing not described
If a predictive test (the reference standard is a later event that the test aims to predict) were any subsequent interventions between test and later event blind to test result?
Not applicable
Was there an appropriate interval between index test(s) and reference standard?
Unclear
Did either all participants or a random sample of participants receive a reference standard test?
Yes
Did all patients receive the same reference standard irrespective of index test result?
Yes
Were all test results including unclear results reported?
Yes
Were all patients included in the analysis?
Yes
What is the risk that the patient flow introduced bias?
Unclear
Comments
Overall risk of bias
At risk of bias Additional comments: Please replace this text and include any additional comments in regards to your risk of bias rating


Jutta's tick icon.png This appraisal has been completed.


Article
Elsafi SH, Alqahtani NI, Zakary NY, Al Zahrani EM. The sensitivity, specificity, predictive values, and likelihood ratios of fecal occult blood test for the detection of colorectal cancer in hospital settings. Clin Exp Gastroenterol 2015;8:279-84 Available from: http://www.ncbi.nlm.nih.gov/pubmed/26392783.
Assigned to
User:Ben.lee-bates
Topic area
Guidelines:Colorectal cancer
Clinical question
Form
Form:Quality appraisal quadas


Section below only relevant for Cancer Council Project Officer

Edit appraisal assignment